; This is a complete BCD floating point package for the 8051 micro-
; controller. It provides 8 digits of accuracy with exponents that
; range from +127 to -127. The mantissa is in packed BCD, while the
; exponent is expressed in pseudo-twos complement. A ZERO exponent
; is used to express the number ZERO. An exponent value of 80H or
; greater than means the exponent is positive, i.e. 80H = E 0,
; 81H = E+1, 82H = E+2 and so on. If the exponent is 7FH or less,
; the exponent is negative, 7FH = E-1, 7EH = E-2, and so on.
; ALL NUMBERS ARE ASSUMED TO BE NORMALIZED and all results are
; normalized after calculation. A normalized mantissa is >=.10 and
; <=.99999999.
;
; The numbers in memory assumed to be stored as follows:
;
; EXPONENT OF ARGUMENT 2   =   VALUE OF ARG_STACK+FP_NUMBER_SIZE
; SIGN OF ARGUMENT 2       =   VALUE OF ARG_STACK+FP_NUMBER_SIZE-1
; DIGIT 78 OF ARGUMENT 2   =   VALUE OF ARG_STACK+FP_NUMBER_SIZE-2
; DIGIT 56 OF ARGUMENT 2   =   VALUE OF ARG_STACK+FP_NUMBER_SIZE-3
; DIGIT 34 OF ARGUMENT 2   =   VALUE OF ARG_STACK+FP_NUMBER_SIZE-4
; DIGIT 12 OF ARGUMENT 2   =   VALUE OF ARG_STACK+FP_NUMBER_SIZE-5
;
; EXPONENT OF ARGUMENT 1   =   VALUE OF ARG_STACK
; SIGN OF ARGUMENT 1       =   VALUE OF ARG_STACK-1
; DIGIT 78 OF ARGUMENT 1   =   VALUE OF ARG_STACK-2
; DIGIT 56 OF ARGUMENT 1   =   VALUE OF ARG_STACK-3
; DIGIT 34 OF ARGUMENT 1   =   VALUE OF ARG_STACK-4
; DIGIT 12 OF ARGUMENT 1   =   VALUE OF ARG_STACK-5
;
; The operations are performed thusly:
;
; ARG_STACK+FP_NUMBER_SIZE = ARG_STACK+FP_NUMBER_SIZE # ARG_STACK
;
; Which is ARGUMENT 2 = ARGUMENT 2 # ARGUMENT 1
;
; Where # can be ADD, SUBTRACT, MULTIPLY OR DIVIDE.
;
; Note that the stack gets popped after an operation.
;
; The FP_COMP instruction POPS the ARG_STACK TWICE and returns status.
;
;**********************************************************************
;
$EJECT
;**********************************************************************
;
; STATUS ON RETURN - After performing an operation (+, -, *, /)
;                    the accumulator contains the following status
;
; ACCUMULATOR - BIT 0 - FLOATING POINT UNDERFLOW OCCURED
;
;             - BIT 1 - FLOATING POINT OVERFLOW OCCURED
;
;             - BIT 2 - RESULT WAS ZER0
;
;             - BIT 3 - DIVIDE BY ZERO ATTEMPTED
;
;             - BIT 4 - NOT USED, 0 RETURNED
;
;             - BIT 5 - NOT USED, 0 RETURNED
;
;             - BIT 6 - NOT USED, 0 RETURNED
;
;             - BIT 7 - NOT USED, 0 RETURNED
;
; NOTE: When underflow occures, a ZERO result is returned.
;       When overflow or divide by zero occures, a result of
;       .99999999 E+127 is returned and it is up to the user
;       to handle these conditions as needed in the program.
;
; NOTE: The Compare instruction returns F0 = 0 if ARG 1 = ARG 2
;       and returns a CARRY FLAG = 1 if ARG 1 is > ARG 2
;
;***********************************************************************
;
$EJECT
;***********************************************************************
;
; The following values MUST be provided by the user
;
;***********************************************************************
;
ARG_STACK_PAGE	EQU	01h	;External memory page for arg stack
ARG_STACK	EQU	24H	;ARGUMENT STACK POINTER
FORMAT		EQU	25H	;LOCATION OF OUTPUT FORMAT BYTE
;OUTPUT		EQU	R5OUT	;CALL LOCATION TO OUTPUT A CHARACTER in R5
CONVT		EQU	0048H	;String addr TO CONVERT NUMBERS
INTGRC		BIT	26H.1	;BIT SET IF INTEGER ERROR
ADD_IN		BIT	26H.3	;DCMPXZ IN BASIC BACKAGE
ZSURP		BIT	26H.6	;ZERO SUPRESSION FOR HEX PRINT
;
;***********************************************************************
;
; The following equates are used internally
;
;***********************************************************************
;
FP_NUMBER_SIZE	EQU	6
DIGIT		EQU	FP_NUMBER_SIZE-2
R0B0		EQU	0
R1B0		EQU	1
UNDERFLOW	EQU	0
OVERFLOW	EQU	1
ZERO		EQU	2
ZERO_DIVIDE	EQU	3
;
;***********************************************************************
$EJECT
	;**************************************************************
	;
	; The following internal locations are used by the math pack
	; ordering is important and the FP_DIGITS must be bit
	; addressable
	;
	;***************************************************************
	;
FP_STATUS	EQU	28H		;NOT used data pointer me
FP_TEMP		EQU	FP_STATUS+1	;NOT USED
FP_CARRY	EQU	FP_STATUS+2	;USED FOR BITS
FP_DIG12	EQU	FP_CARRY+1
FP_DIG34	EQU	FP_CARRY+2
FP_DIG56	EQU	FP_CARRY+3
FP_DIG78	EQU	FP_CARRY+4
FP_SIGN		EQU	FP_CARRY+5
FP_EXP		EQU	FP_CARRY+6
MSIGN		BIT	FP_SIGN.0
XSIGN		BIT	FP_CARRY.0
FOUND_RADIX	BIT	FP_CARRY.1
FIRST_RADIX	BIT	FP_CARRY.2
DONE_LOAD	BIT	FP_CARRY.3
FP_NIB1		EQU	FP_DIG12
FP_NIB2		EQU	FP_NIB1+1
FP_NIB3		EQU	FP_NIB1+2
FP_NIB4		EQU	FP_NIB1+3
FP_NIB5		EQU	FP_NIB1+4
FP_NIB6		EQU	FP_NIB1+5
FP_NIB7		EQU	FP_NIB1+6
FP_NIB8		EQU	FP_NIB1+7
FP_ACCX		EQU	FP_NIB1+8
FP_ACCC		EQU	FP_NIB1+9
FP_ACC1		EQU	FP_NIB1+10
FP_ACC2		EQU	FP_NIB1+11
FP_ACC3		EQU	FP_NIB1+12
FP_ACC4		EQU	FP_NIB1+13
FP_ACC5		EQU	FP_NIB1+14
FP_ACC6		EQU	FP_NIB1+15
FP_ACC7		EQU	FP_NIB1+16
FP_ACC8		EQU	FP_NIB1+17
FP_ACCS		EQU	FP_NIB1+18
	;
$EJECT
	
FP_BASE		EQU	$

	;**************************************************************
	;
	; The floating point entry points and jump table
	;
	;**************************************************************
	;
	AJMP	FLOATING_ADD
	AJMP	FLOATING_SUB
	AJMP	FLOATING_COMP
	AJMP	FLOATING_MUL
	AJMP	FLOATING_DIV
	AJMP	HEXSCAN
	AJMP	FLOATING_POINT_INPUT
	AJMP	FLOATING_POINT_OUTPUT
	AJMP	CONVERT_BINARY_TO_ASCII_STRING
	AJMP	CONVERT_ASCII_STRING_TO_BINARY
	AJMP	MULNUM10
	AJMP	HEXOUT
;
; the remaining jump to routines were extracted from basic52 
; by me to make the floating point software stand alone
;
	AJMP	PUSHR2R0			; INTEGER to FLOAT
	AJMP	IFIX				; FLOAT to INTEGER
	AJMP	PUSHAS				; PUSH R2:R0 TO ARGUMENT
	AJMP	POPAS				; POP ARGUMENT TO R3:R1
	AJMP	MOVAS				; COPY ARGUMENT
	AJMP	AINT				; INT FUNCTION 
	AJMP	PUSHC				; PUSH ARG IN DPTR TO STACK
	;
$EJECT
	;
FLOATING_SUB:
	;
	MOV	P2,#ARG_STACK_PAGE
	MOV	R0,ARG_STACK
	DEC	R0		;POINT TO SIGN
	MOVX	A,@R0		;READ SIGN
	CPL	ACC.0
	MOVX	@R0,A
	;
	;AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
	;
FLOATING_ADD:
	;
	;AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
	;
	;
	ACALL 	MDES1		;R7=TOS EXP, R6=TOS-1 EXP, R4=TOS SIGN
				;R3=TOS-1 SIGN, OPERATION IS R1 # R0
	;
	MOV	A,R7		;GET TOS EXPONENT 
	JZ	POP_AND_EXIT	;IF TOS=0 THEN POP AND EXIT
	CJNE	R6,#0,LOAD1	;CLEAR CARRY EXIT IF ZERO
	;
	;**************************************************************
	;
SWAP_AND_EXIT:	; Swap external args and return
	;
	;**************************************************************
	;
	ACALL	LOAD_POINTERS
	MOV	R7,#FP_NUMBER_SIZE
	;
SE1:	MOVX	A,@R0		;SWAP THE ARGUMENTS
	MOVX	@R1,A
	DEC	R0
	DEC	R1
	DJNZ	R7,SE1
	;
POP_AND_EXIT:
	;
	MOV	A,ARG_STACK	;POP THE STACK
	ADD	A,#FP_NUMBER_SIZE
	MOV	ARG_STACK,A
	CLR	A
	RET
	;
	;
LOAD1:	SUBB	A,R6		;A = ARG 1 EXP - ARG 2 EXP
	MOV	FP_EXP,R7	;SAVE EXPONENT AND SIGN
	MOV	FP_SIGN,R4
	JNC	LOAD2		;ARG1 EXPONENT IS LARGER OR SAME
	MOV	FP_EXP,R6
	MOV	FP_SIGN,R3
	CPL	A
	INC	A		;COMPENSATE FOR EXP DELTA
	XCH	A,R0		;FORCE R0 TO POINT AT THE LARGEST
	XCH	A,R1		;EXPONENT
	XCH	A,R0
	;
LOAD2:	MOV	R7,A		;SAVE THE EXPONENT DELTA IN R7
	CLR	ADD_IN
	CJNE	R5,#0,$+5
	SETB	ADD_IN
	;
$EJECT
	; Load the R1 mantissa
	;
	ACALL	LOADR1_MANTISSA	;LOAD THE SMALLEST NUMBER
	;
	; Now align the number to the delta exponent
	; R4 points to the string of the last digits lost
	;
	CJNE	R7,#DIGIT+DIGIT+3,$+3
	JC	$+4
	MOV	R7,#DIGIT+DIGIT+2
	;
	MOV	FP_CARRY,#00	;CLEAR THE CARRY
	ACALL	RIGHT		;SHIFT THE NUMBER
	;
	; Set up for addition and subtraction
	;
	MOV	R7,#DIGIT	;LOOP COUNT
	MOV	R1,#FP_DIG78
	MOV	A,#9EH
	CLR	C
	SUBB	A,R4
	DA	A
	XCH	A,R4
	JNZ	$+3
	MOV	R4,A
	CJNE	A,#50H,$+3	;TEST FOR SUBTRACTION
	JNB	ADD_IN,SUBLP	;DO SUBTRACTION IF NO ADD_IN
	CPL	C		;FLIP CARRY FOR ADDITION
	ACALL	ADDLP		;DO ADDITION
	;
	JNC	ADD_R
	INC	FP_CARRY
	MOV	R7,#1
	ACALL	RIGHT
	ACALL	INC_FP_EXP	;SHIFT AND BUMP EXPONENT
	;
ADD_R:	AJMP	STORE_ALIGN_TEST_AND_EXIT
	;
ADDLP:	MOVX	A,@R0
	ADDC	A,@R1
	DA	A
	MOV	@R1,A
	DEC	R0
	DEC	R1
	DJNZ	R7,ADDLP	;LOOP UNTIL DONE
	RET
	;
$EJECT
	;
SUBLP:	MOVX	A,@R0		;NOW DO SUBTRACTION
	MOV	R6,A
	CLR	A
	ADDC	A,#99H
	SUBB	A,@R1
	ADD	A,R6
	DA	A
	MOV	@R1,A
	DEC	R0
	DEC	R1
	DJNZ	R7,SUBLP
	JC	FSUB6
	;
$EJECT
	;
	; Need to complement the result and sign because the floating
	; point accumulator mantissa was larger than the external
	; memory and their signs were equal.
	;
	CPL	FP_SIGN.0
	MOV	R1,#FP_DIG78
	MOV	R7,#DIGIT	;LOOP COUNT
	;
FSUB5:	MOV	A,#9AH
	SUBB	A,@R1
	ADD	A,#0
	DA	A
	MOV	@R1,A
	DEC	R1
	CPL	C
	DJNZ	R7,FSUB5	;LOOP
	;
	; Now see how many zeros their are
	;
FSUB6:	MOV	R0,#FP_DIG12
	MOV	R7,#0
	;
FSUB7:	MOV	A,@R0
	JNZ	FSUB8
	INC	R7
	INC	R7
	INC	R0
	CJNE	R0,#FP_SIGN,FSUB7
	AJMP	ZERO_AND_EXIT
	;
FSUB8:	CJNE	A,#10H,$+3
	JNC	FSUB9
	INC	R7
	;
	; Now R7 has the number of leading zeros in the FP ACC
	;
FSUB9:	MOV	A,FP_EXP	;GET THE OLD EXPONENT
	CLR	C
	SUBB	A,R7		;SUBTRACT FROM THE NUMBER OF ZEROS
	JZ	FSUB10
	JC	FSUB10
	;
	MOV	FP_EXP,A	;SAVE THE NEW EXPONENT
	;
	ACALL	LEFT1		;SHIFT THE FP ACC
	MOV	FP_CARRY,#0
	AJMP	STORE_ALIGN_TEST_AND_EXIT
	;
FSUB10:	AJMP	UNDERFLOW_AND_EXIT
	;
$EJECT
	;***************************************************************
	;
FLOATING_COMP:	; Compare two floating point numbers
		; used for relational operations and is faster
		; than subtraction. ON RETURN, The carry is set
		; if ARG1 is > ARG2, else carry is not set
		; if ARG1 = ARG2, F0 gets set
	;
	;***************************************************************
	;
	ACALL	MDES1		;SET UP THE REGISTERS
	MOV	A,ARG_STACK
	ADD	A,#FP_NUMBER_SIZE+FP_NUMBER_SIZE
	MOV	ARG_STACK,A	;POP THE STACK TWICE, CLEAR THE CARRY
	MOV	A,R6		;CHECK OUT EXPONENTS
	CLR	F0
        CLR     C
	SUBB	A,R7
	JZ	EXPONENTS_EQUAL
	JC	ARG1_EXP_IS_LARGER
	;
	; Now the ARG2 EXPONENT is > ARG1 EXPONENT
	;
SIGNS_DIFFERENT:
	;
	MOV	A,R3		;SEE IF SIGN OF ARG2 IS POSITIVE
	SJMP	$+3
	;
ARG1_EXP_IS_LARGER:
	;
	MOV	A,R4		;GET THE SIGN OF ARG1 EXPONENT
	JZ	$+3
	CPL	C
	RET
	;
EXPONENTS_EQUAL:
	;
	; First, test the sign, then the mantissa
	;
	CJNE	R5,#0,SIGNS_DIFFERENT
	;
BOTH_PLUS:
	;
	MOV	R7,#DIGIT	;POINT AT MS DIGIT
	DEC	R0
	DEC	R0
	DEC	R0
	DEC	R1
	DEC	R1
	DEC	R1
	;
	; Now do the compare
	;
CLOOP:	MOVX	A,@R0
	MOV	R6,A
	MOVX	A,@R1
	SUBB	A,R6
	JNZ	ARG1_EXP_IS_LARGER
	INC	R0
	INC	R1
	DJNZ	R7,CLOOP
	;
	; If here, the numbers are the same, the carry is cleared
	;
	SETB	F0
	RET			;EXIT WITH EQUAL
	;
$EJECT
;MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
;
FLOATING_MUL:	; Floating point multiply
;
;MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
;
	ACALL	MUL_DIV_EXP_AND_SIGN
	;
	; check for zero exponents
	;
	CJNE	R6,#00,$+5	;ARG 2 EXP ZERO?
	AJMP	ZERO_AND_EXIT
	;
	; calculate the exponent
	;
FMUL1:	MOV	FP_SIGN,R5	;SAVE THE SIGN, IN CASE OF FAILURE
	;
	MOV	A,R7
	JZ	FMUL1-2
	ADD	A,R6		;ADD THE EXPONENTS
	JB	ACC.7,FMUL_OVER
	JBC	CY,FMUL2	;SEE IF CARRY IS SET
	;
	AJMP	UNDERFLOW_AND_EXIT
	;
FMUL_OVER:
	;
	JNC	FMUL2		;OK IF SET
	;
FOV:	AJMP	OVERFLOW_AND_EXIT
	;
FMUL2:	SUBB	A,#129		;SUBTRACT THE EXPONENT BIAS
	MOV	R6,A		;SAVE IT FOR LATER
	;
	; Unpack and load R0
	;
	ACALL	UNPACK_R0
	;
	; Now set up for loop multiply
	;
	MOV	R3,#DIGIT
	MOV	R4,R1B0
	;
$EJECT
	;
	; Now, do the multiply and accumulate the product
	;
FMUL3:	MOV	R1B0,R4
	MOVX	A,@R1
	MOV	R2,A
	ACALL	MUL_NIBBLE
	;
	MOV	A,R2
	SWAP	A
	ACALL	MUL_NIBBLE
	DEC	R4
	DJNZ	R3,FMUL3
	;
	; Now, pack and restore the sign
	;
	MOV	FP_EXP,R6
	MOV	FP_SIGN,R5
	AJMP	PACK		;FINISH IT OFF
	;
$EJECT
	;DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD
	;
FLOATING_DIV:
	;
	;DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD
	;
	ACALL	MDES1
	;
	; Check the exponents
	;
	MOV	FP_SIGN,R5	;SAVE THE SIGN
	CJNE	R7,#0,DIV0	;CLEARS THE CARRY
	ACALL	OVERFLOW_AND_EXIT
	CLR	A
	SETB	ACC.ZERO_DIVIDE
	RET
	;
DIV0:	MOV	A,R6		;GET EXPONENT
	JZ	FMUL1-2		;EXIT IF ZERO
	SUBB	A,R7		;DELTA EXPONENT
	JB	ACC.7,D_UNDER
	JNC	DIV3
	AJMP	UNDERFLOW_AND_EXIT
	;
D_UNDER:JNC	FOV
	;
DIV3:	ADD	A,#129		;CORRECTLY BIAS THE EXPONENT
	MOV	FP_EXP,A	;SAVE THE EXPONENT
	ACALL	LOADR1_MANTISSA	;LOAD THE DIVIDED
	;
	MOV	R2,#FP_ACCC	;SAVE LOCATION
	MOV	R3,R0B0		;SAVE POINTER IN R3
	MOV	FP_CARRY,#0	;ZERO CARRY BYTE
	;
DIV4:	MOV	R5,#0FFH	;LOOP COUNT
	SETB	C
	;
DIV5:	MOV	R0B0,R3		;RESTORE THE EXTERNAL POINTER
	MOV	R1,#FP_DIG78	;SET UP INTERNAL POINTER
	MOV	R7,#DIGIT	;LOOP COUNT
	JNC	DIV7		;EXIT IF NO CARRY
	;
DIV6:	MOVX	A,@R0		;DO ACCUMLATION
	MOV	R6,A
	CLR	A
	ADDC	A,#99H
	SUBB	A,R6
	ADD	A,@R1
	DA	A
	MOV	@R1,A
	DEC	R0
	DEC	R1
	DJNZ	R7,DIV6		;LOOP
	;
	INC	R5		;SUBTRACT COUNTER
	JC	DIV5		;KEEP LOOPING IF CARRY
	MOV	A,@R1		;GET CARRY
	SUBB	A,#1		;CARRY IS CLEARED
	MOV	@R1,A		;SAVE CARRY DIGIT
	CPL	C
	SJMP	DIV5		;LOOP
	;
	; Restore the result if carry was found
	;
DIV7:	ACALL	ADDLP		;ADD NUMBER BACK
	MOV	@R1,#0		;CLEAR CARRY
	MOV	R0B0,R2		;GET SAVE COUNTER
	MOV	@R0,5		;SAVE COUNT BYTE
	;
	INC	R2		;ADJUST SAVE COUNTER
	MOV	R7,#1		;BUMP DIVIDEND
	ACALL	LEFT
	CJNE	R2,#FP_ACC8+2,DIV4
	;
	DJNZ	FP_EXP,DIV8
	AJMP	UNDERFLOW_AND_EXIT
	;
DIV8:	MOV	FP_CARRY,#0
	;
$EJECT
	;***************************************************************
	;
PACK:	; Pack the mantissa
	;
	;***************************************************************
	;
	; First, set up the pointers
	;
	MOV	R0,#FP_ACCC
	MOV	A,@R0		;GET FP_ACCC
	MOV	R6,A		;SAVE FOR ZERO COUNT
	JZ	PACK0		;JUMP OVER IF ZERO
	ACALL	INC_FP_EXP	;BUMP THE EXPONENT
	DEC	R0
	;